Spinal interlaminar fixation including lumbosacral fusion and correcting scoliotic curves are well known and frequently used medical procedures. Spinal fixation systems, frequently used to correct problems in the lumbar, are installed on opposite sides of the sacrum adjacent to the lumbosacral junction. Such systems often include a pair of rods which are placed on opposite sides of the portion of the spine which is intended to be fused. Pedicle, lateral and oblique mounting means may be used to secure the rods relative to the desired portion of the spine which will be fused by the fixation system.
Crosslinking of spinal instrumentation or spinal rods is designed to prevent rod migration and to increase stiffness of the surgical construct. Even with rigid crosslinking, all spinal constructs are designed to provide only temporary fixation until solid bone fusion has been completed. Without adequate bone fusion, fatigue endurance of the construct will be exceeded, which may cause rod fracture.
Various connectors and cross-links have been used to attach spinal rods to each other when the rods have been installed at the desired location adjacent to the patient's spine. Examples of such spinal fixation systems and related equipment are shown in U.S. Pat. Nos. 4,790,297 and 4,913,134 issued to Eduardo R. Luque. Many of the presently available spinal fixation systems require placing extra hardware such as eyebolts on the spinal rods before attaching the rod to pedicle screws or hooks at selected locations along the patient's spine. Also, presently available fixation systems require careful alignment of the hardware used to connect the spinal rods with each other.
A need has thus arisen for improved connectors to attach spinal rods to each other without requiring additional manipulation of the rods or placing the rods in a specific geometric relationship with respect to each other, and at the same time reducing requirements to assemble small pieces of hardware during the surgical procedure.